Bearing and fluid passage structure for flexible diaphragm fluid cylinders



Feb. 15, 1955 M. M. SEELOFF 23 BEARING AND FLUID PASS E STRUCTURE 50R BLE FLEXI DIAPHRAGM F D CYLINDER Filed July 23, 1953 INVENT MELVIN M. SEELO ATTORNEY United States Patent Oflice 2,102,023 BEARING AND rwm PASSAGE srnucruna llggfis FLEXIBLE DIAPHRAGM FLUID CYLIN- Melvin M. SeeIolL Wan'en, Ohio, assignor to The Taylorgliinfield Corporation, Warren, Ohio, a corporation of g more particularly to certain improvements 'in the construction' of low friction air motors and the like.

As an overall object, the present invention seeks to provide an air cylinder of the general type employing flexible diaphragm packing elements, wherein are mcorporated certain novel features of construction tending to simplify and improve the construction and operation of such'cylinders. a

A more specific object of the invention resides in the provision of adiaphragm-type air-operated cylinder device which is characterized by improved means for guiding the movable piston member of the device in longitudinal movement upon the application of air pressure to the device.

In connection with the above, it is yet another ob ect of the invention to provide a novel diaphragm-type an cylinder comprisingan' elongated generally cup-shaped piston member and having a relatively elongated means for guiding the piston in longitudinal movement, wherein the cylinder device as a whole is relatively short and compact inrelation to the overall operating str oke thereof.

More particularly. it is an ob ect of this invention to provide an improved air cylinder device of the type generally described above, comprising a cup-shaped piston member, wherein the means for guiding the piston mem her in longitudinal movement is adapted to be received in nested relation within longitudinally extending side walls of the cup-shaped piston member to thereby avoid unnecessary lengthening of the cylinder device.

Another object of the invention is the provision of an improved diaphragm operated air cylinder device employing flexible diaphragms in place of conventional piston packings, wherein means are provided for securing the outer edges of the diaphragms between the principal cylinder body and the end caps therefor whereby the diaphragms serve i'phan additional capacity as gasket members, preventing e passage of fluid between the cylinder body and the end caps.

Another object of the invention is the provision of a novel air cylinder device of the type and having the characteristics set forth above which is, in, addition, readily and economically manufactured and easily adapted for various use requirements.

The above and other objects and advantages of the invention will become apparent upon full consideration of the following detailed specification and accompanying drawing wherein is disclosed acertatn preferred embodiment of the invention.

{In the drawing: Figure l is a longitudinal section view of a fluid cylinder constructed in accordance with the teachings of my invention;

Figure 2 is a section view taken along line II-II of which receive the end portions of the cylindrical body member 10. And a plurality of circumferentially spaced bolts 15 are provided to compress the end caps 11 and 12 Patented Feb. 15, 1955 against the central member 10 and to'thereby provides rigid cylinder assembly.

Housed within the interior of the cylinder structure,

and movable longitudinally therein, is a piston member 16 which is generally cup-shaped,'h'aving longitudinally extending cylindrical side wall 17. And it is in accordance with the teachings'of the invention that the side wall 17 be spaced slightly from the interior side wall of the cylindrical body-member 10. Rigidly secured to the piston member 16, and extending outwardly therefrom in the same direction as the side wall 17, is an operating or piston rod 18 which, in accordance with general practice, may be attached to a machine'component, not shown.

In place of conventional piston packings the present invention contemplates the use of flexible diaphragms 19 and 20 which are secured to the piston 16, at each axial end thereof, and to the side walls of the cylinder structure. The arrangement is such that upon application of air pressure to one end or the other of the apparatus the piston 16 will be caused to move in a more or less frictionless manner, while the diaphragms 19 and 20 merely roll along the side walls 17 of the piston and along the side walls of the cylindrical member 10. -And it is of course contemplated that the annular clearance between the piston 16 and body member 10 will be suilicient to permit the diaphragms to freely flex during longitudinal movement of the piston.v However, it is further contemplated that such clearance be no greater than necessary for this purpose.

In accordance with the teachings of the invention the diaphragms 19 and 20 are secured at their outer edges between the body member 10 andend cap members 11 and 12, substantially as shown in Figure 1, so that when the apparatus is assembled the diaphragms may be utilized in an additional capacity as a sealing agent to prevent the escape of air or other fluid from the cylinder.-

' Bolts 15, of course, serve to securely clamp .the outer edges of the diaphragms in properly assembled relation.

The inner edge of the forward diaphragm 19 is preferably secured by a cap 21, which is in turn secured by a suitable nut 22 which retains the piston 16 and operating rod 18 in assembled relation. Likewise, the inner edge of the rear or rod end diaphragm 20 is secured by means of an annular cap 23 which is secured to the side wall 17 by means of a plurality ofcap screws 24.

Also in accordance with the teachings of the invention I have provided an improved arrangement for guiding the longitudinal movement of the piston 16 and operating rod 18, which guiding arrangement comprises a forward bearing member 25, of bronze for example, which confines and guides the rod 18 adjacent the extreme outer end of the end cap 12, and a second bearing member 26,

which is spaced substantially inwardly of the bearing 25 so that the rod '18 is provided with guidance at two widely spaced areas.

In order to provide for a maximum spacing between the bearing members 25 and 26, without unnecessarily increasing the overall length of the cylinder-assembly, my invention teaches the provision of a forwardly extending annular mounting 27 for the bearing 26, which mounting is preferably formed as an integral part of the end cap 12. As illustrated, the annular bearing mounting 27 is of a lesser diameter than the internal diameter of the side wall 17 of iston 16 so that during movement of the piston to e right the mounting 27 is re- 'ceived internally of the piston 16.

ltrwill be understood, of course, that in the construction of diaphragm type air motor it is necessary, or at a least highly desirable to construct the piston member with a longitudinlly extending side wall of sufficient length that there will be provided a rigid backing for the flexible diaphragms during all stages of movement of the piston. And it will further be apparent that the necessary length of the side wall or piston will bear a direct relation to the maximum operating stroke of the appa ratus. Thus, in a cylinder device t adapted for long stroke operation, the side wall of the piston must be relatively long. While in apparatus intended for short stroke operation the side wall may be proportionately shorter.

Likewise, it will be understood that where a piston is intended to move through a long operating stroke a more as the same moves toward such bearing mounting.

substantial guidance is required. And in accordance with the teachings of my invention this may be readily provided since as the length of the side wall is increased to provide long stroke operation, the length of the bearing mounting 27, and consequently the spacing between the bearing areas, may be increased an equal amount without unnecessarily lengthening the assembly as a whole.

In the cylinder device herein illustrated there is provided means including resilient collapsible valving members 28 and metering valves 29 for cushioning the end stroke of the piston 16, such means being fully described in co-pending application Ser. No. 357,155, filed May 25, 1953, by Donald M. Campbell. In accordance with the teachings of this 'last mentioned invention there is provided at the open end of the annular bearing mount ng 27 a valving surface which is adapted to receive valving member 28 to prevent a normal outflow of air from the cylinder and thereby to cushion the end stroke thereof. Hence, in this embodiment it is necessary to locate the bearing member 26 somewhat inwardly of the open end of the mounting 27. However, it will be readily understood that in normal fluid cylinder applications, not employing means to cushion the end stroke of the. cylinder, the bearing 26 may be located at the extreme end of the mounting 27 whereby to further improve the guidance of the operating rod 18.

Also in accordance with the disclosure of the above identified application it is desirable to provide an annular air passage about the operating rod 18 so that cushioning of the end stroke of the cylinder may be more effectively carried out. Thus, in the present embodiment of the invention I may provide a plurality of longitudinally extending circumferentially spaced grooves or recesses 30 which are arranged to permit a substantially unimpeded flow of air about the operating rod 18 and bearing 26 therefor, while yet providing a suflicient area of contact with the bearing 26 to firmly supportthe same in its mounting 27. This feature may, of course, be eliminated where a cushioning of the end stroke of the piston is not employed.

It should now be apparent that I have accomplished the objects initially set forth. My improved construction V for diaphragm type air cylinders is such that there is substantial guidance for the movable piston during longitudinal movement while the piston itself makes no contact with the walls of the cylinder. It has been heretofore proposed, of course, to provide a piston member of having a portion of its side wall of increased diameter whereby guidance would be afforded by a single bearing guiding the piston or operating rod, in combination with a bearing contact between the side walls of the cylinder and the enlarged portion of the piston. This construction, however, necessitates the use of a piston having side walls of substantial length in relation to the length of the operating stroke thereby afforded. And,

in addition, there is substantial friction and .wear between the piston and cylinder parts, necessitating the use of wear resistant materials for such parts.

According to the teachings of my present invention I may provide an annular clearance space along the entire longitudinal length of the piston 16 so that the same may be kept as short as possible for the desired length of operating stroke. Moreover, by providing for accurately guided longitudinal movement of the piston I may maintain such annular clearance space only as large as necessary to permit free flexure of the diaphragms 19 and 20. And by this arrangement it is assured that a piston of maximum effective area is aflorded, which in turn reduces the strain upon the flexible diaphragms.

Perhaps the principal or dominating characteristic of ,my invention resides in the use, in combination with a cup-shaped piston member having a longitudinally extending side wall, of a longitudinally extending bearing mounting or bearing portion which projects inwardly of the end of the cylinder and which is adapted to be received within the interior of the side wall of the piston y this construction I may provide a pair of widely spaced bearing areas (or, if desired, a single elongated bearing) whereby accurate and substantial guidance of the operating rod and piston is afforded. In this respect, it will further be noted that it is usually suflicient if the pro be, may be at all times in proportion to the length of travel of the piston so adequateguidance of the piston 18 alforded under all conditions. This is occasioned by the fact that in practical diaphragm-type air cylinders the side wall of the piston, in order to provide proper backing for the flexible diaphragms, must increase in length in proportion to increases in length of the operating stroke.

Another advantage of .my invention results from guiding the piston wholly through its operating rod, and this is that the piston and cylinder parts, other than the operating rod and bearings 25 and 26 may be constructed of soft and lightweight materials, such as aluminum, for example, which provides for substantial economies in the manufacture of the apparatus, as well as facilitating subsequent shipping and handling thereof.

Still another novel and advantageous feature of the invention resides in the use of the flexible diaphragm members 19 and 20 in'an additional capacity as sealing members. Thus, in order to secure the outer edges of the diaphragm members I merely clamp the outer peripheral portions of the same between the main body member and the end caps of the cylinder device. And by this arrangement the diaphragms serve additionally to prevent the escape of operating fluid from these points.

It should be understood, however, that the embodiment herein shown and specifically described is intended to be illustrative only, and reference should therefore be had to the following appended claims in determining the full scope of the invention.

I claim:

1. In a fluid cylinder device of the type comprising a cylinder assembly, a piston movable in said cylinder assembly, an operating rod connecting said piston and projecting outwardly of one end of said cylinder assembly, and a pair of flexible diaphragms connecting said piston and cylinder assembly; the improvement characterized by said piston having a longitudinally extending side. wall providing backing for said diaphragms, said piston and side wall being of lesser diameter throughout than the interior of said cylinder assembly whereby to provide an annular clearance for the friction-free move-' ment of said piston, means to guide said piston in longitudinal movement comprising a sleeve-like bearing insert, and means projecting from said one end and adapted to be received annularly between said operating rod and said side wall for supporting said bearing insert, said projecting means comprising an integral part of said cylinder assembly and having a plurality of longitudinally extending circumferentially spaced grooves providing passageways for fluid about said bearing and rod.

2. In a fluid cylinder device of the type comprising a cylinder assembly, a piston movable in said cylinderassembly, an operating rod connecting said piston and projecting outwardly of one end of said cylinder assembly, a flexible diaphragm connecting said piston and cylinder assembly, said cylinder assembly having means projecting inwardly from one end thereof constituting bearing means for guiding said operating rod; the improvement in said last mentioned means characterized by said bearing means comprising a sleeve-like bearing insert and means projecting inwardly from said'one end for supporting said bearing insert, said last mentioned means having a plurality of longitudinally extending grooves of greater length than said bearing insert whereby to provide for the passage of air into said assembly about the outer wall of said insert.

References Cited in the file of this patent UNITED STATES PATENTS 2,028,371 Wiltse Ian. 21, 1936 FOREIGN PATENTS 3,058 Great Britain 1884 660,169 France Feb. 12, 1929 

